1. Field of the Disclosure
This disclosure relates generally to downhole loads operated by directly coupled alternator motor units.
2. Background of the Art
Wellbores for production of hydrocarbons are drilled using a drill string that includes a drilling assembly (also referred to as a “bottomhole assembly”) attached to a bottom end of a tubular. A drill bit is attached to the bottom end of the BHA. The drill bit is rotated by rotating the drill string and/or by a mud motor in the BHA to drill the wellbore. The BHA may include various devices that are operated by electrical motors. The wellbore temperature can exceed 200 degrees. At high temperatures, the effort on the electronic side of the electrical motors is very high to control the speed and the position of a motor drive. However it is not always necessary to precisely control the speed and/or position of the motor drive.
The disclosure herein provides apparatus having a power unit that includes an electrical motor driven by a substantially directly coupled alternator that includes relatively minimal or no electronics.